In a reaction of oxidizing an organic substrate, such as an amine, a hydrocarbon, an aldehyde, a ketone, or an alcohol with oxygen, use of a variety of catalysts has hitherto been studied, and reported. As such a catalyst, for example, Patent Document 1 describes a catalyst comprising a hydrazyl radical or a hydrazine compound and a transition metal compound, the catalyst being used in a reaction of oxidizing an amine with oxygen, and Patent Document 2 describes a catalyst comprising an N-hydroxy cyclic imide and a transition metal compound, the catalyst being used in a reaction of oxidizing a hydrocarbon, an aldehyde, a ketone or an alcohol with oxygen.